The present invention concerns weaving. In particular, it is a woven material produced using tape-like warp and tape-like weft through the employment of a rotary type shedding means which also functions as a direct specific-weave patterning means and a pick guiding means.
The conventional 2D-weaving process is employed for producing technical fabrics for numerous applications. For example, woven fabric structures are used in the manufacture of composite materials, geotextiles, filter fabrics, fabrics for agricultural use etc. In the production of such fabrics usually same yarns/filaments or tapes of homogenous constructional constitution (e.g. comprising similar fibres) are used. With a view to produce certain novel woven technical items, use of flat tape-like materials of non-homogenous constructional constitution (i.e. strips/narrow films/ribbon/band etc. of non-homogenous constructional constitution) could also be considered in many of the above said applications because such a woven item will have the advantages of relatively less crimp, higher cover factor (i.e. larger solid surface-area of the fabric due to lesser crimp), being produced quickly due to the increased width size of the input materials, etc. For example, woven non-homogeneous tape-like prepregs of parallel filaments of blended fibres e.g. carbon, glass etc. (for uniform distribution of individual fibre types in woven material and improved performance of woven material with respect to cost) embedded in a suitable matrix could be used in certain laminate type composite applications, woven tapes of sandwich/layered construction in which are combined layers of one or more type of fibre, or blend of fibres, and either one or more type of polymeric film, or one or more type of metal foil could be used as a protective material in ballistics application or as a thermal/light reflector, woven perforated tapes could be used as a filtering medium (e.g. geotextiles, in food industry), woven corrugated tapes in certain conveyor belts etc. Such different types of tapes of non-homogeneous constructional constitution do not appear to have been used earlier as warp and weft to produce novel woven materials.
However, the conventional weaving elements which directly interact with the yearns, such as heald-wires, reed and weft transporting means (shuttles, rapier heads etc.) cannot be satisfactorily employed. This is because these conventional weaving elements are designed to handle only yarns which have a circle-like cross-section and not materials which are flat such as tapes, i.e. the cross-section profile of such materials being rectangle-like. If the conventional weaving elements are employed to process flat tape-like materials, they will cause deformation of the tape-like materials leading to an unsatisfactory and an unacceptable product for the given end-application. Furthermore, the use of these elements can cause weakening of the flat tape-like materials through increased abrasion and hence render the employed materials, which are usually expensive high-performance fibrous materials, unsuitable for its intended payload.
Another important factor concerns the inability of, for example the heald wires, to handle delicately the fibrous materials which are brittle in nature such as ceramic, carbon, glass, certain synthetics etc. Elements such as the healdwires will cause severe and sharp bends to the brittle fibrous materials, as also to the other material types like metallic foil strips, during the shedding operation because of the need to lift the warp yarns sufficiently high to form a clear shed. The operation of shedding using the conventional means will therefore adversely affect the fabric production and the fabric quality by way of fibre breakages and material deformation respectively. Yet another related important drawback is that concerning the inability of the healdwires to handle tape-like materials of relatively high thickness and stiffness compared with the usual thickness (diameter) and pliability of the yarn materials.
Further, it is necessary to lay the tape-like pick into the shed dependably and without causing abrasion to the warp material from the weft inserting means (shuttle, rapier, projectile etc.). The abrasion of the warp material by the weft inserting means is to be avoided to preserve the properties of the high-performance materials which are usually used so that the performance and the quality of the product is not diminished. In conventional shuttleless weaving practice, use is made of a suitable guide channel to prevent the abrasion of the warp yarns from the weft inserting means and to guide the insertion of the pick into the open shed. However, such a means is a separate unit from the shedding means and works independently, or in combination with the reed. Such a guiding means usually forms part of the sley assembly on which is mounted the beating-up reed. The incorporation in a weaving device of such a pick guiding means is independent of the shedding means, and is located far away from the cloth-fell position during the picking operation. Because of such separate locations of the arrangements of the shedding means and the pick guiding means, the lifting height of the shed has to be necessarily increased to obtain a clear shed for unobstructed pick insertion. As a consequence, the warp yarns are repeatedly subjected to high tensions during the shedding operation which leads to yarn breaks, which in turn, adversely affects the fabric production and quality. Clearly to prevent generation of high tensions in the warp ends, it is desirable to keep the shed height as low as possible, i.e. resonably close to the height of the employed weft inserting means such as rapier, projectile and shuttle, to enable unobstructed weft insertion.
Also, in the processing of flat tape-like materials, it is desirable to not beat-up the inserted flat tape-like weft into the position of cloth-fell using a reed with a view to eliminate the associated lateral deformation of the tape-like weft. Going by this short-coming and also the other above-mentioned limitations, it is clear that the conventional design of weaving elements cannot be applied satisfactorily in the production of woven items comprising tape-like warp and weft. Hence, a suitable weaving alternative is necessary. The alternative efficient way would be lay the pick directly into the fabric-fell so that the conventional reciprocating beating-up operations using a reed can be avoided. In the circumstances, the shedding means will have to be brought close to the cloth-fell position so that the weft can be closely laid into the cloth-fell. In bringing the shedding means close to the cloth-fell position, there is the advantage in that the cross-section size of the shed, namely the shed-height and the shed-depth, will be substantially reduced as the lifting-height of the shed will not be required to be enormous compared with the height of the employed weft inserting means. Such a reduction in the shed""s cross-sectional size will reduce (i) the generation of high tensions in the warp ends, which is desirable as pointed out earlier, and (ii) the distance between the cloth-fell position and the back-rest roll position, i.e. the depth of the weaving machine. As a consequence the depth of the weaving machine will be substantially reduced making the weaving device very compact. Thus if the pick can be laid closely to the fabric-fell, there is a benefit in that the conventional reciprocating beating-up operation will become redundant, and as a consequence, the weaving process will tend to become highly simplified besides eliminating the risk of causing deformation and damage to the tape-like warp and weft materials.
Another important requirement when processing tape-like warp ends is to produce specified weave patterns such as plain weave, twill weaves, satin weaves etc. Because tape-like warp ends are greatly wider in size than yarns, they present the unique ease of being selected directly for manipulation. The yarns and filaments, because of their relatively small cross-sectional size, cannot be selected directly for manipulation as evidenced by the placement of the weave pattern selecting means such as the cams, dobby and the jacquard far away from the warp ends which in turn necessitates the use of heald wires. Therefore the ease of direct manipulation offered by the flat tape-like material creates the possibility of combining such a direct weave patterning means with the shedding means itself. Such a combining of these two different functional means would reduce the number of related components to just one in accordance with the present invention. Such a combining of two different functional means will be advantageous in that the weaving process becomes highly simplified in technical terms and profitable in economic terms due to the associated low maintenance, overhead and running costs. Also, the manufacturing time and costs of the weaving device itself stands to be reduced. As only a limited range of simple weave patterns are necessary in the production of woven technical fabrics, unlike in the production of clothing and furnishing fabrics which may require complex weave patterning means like dobby and jacquard for aesthetic reason, a specific prearranged or programmed simple weave patterning means can be combined with the shedding means without any complication as disclosed in the present invention. Such a combined means would be capable of forming the shed of the specified weave pattern only.
It is now amply clear that there is a need, and it is also desirable, to have a weaving device incorporating a single but multi-purpose component which functions as a shedding means, a specific weave patterning means, and a pick guiding means for the satisfactory processing of the flat tape-like materials of any material type capable of being woven, including brittle continuous-fibre types, to aid the production of quality woven items for certain technical applications.
Although the above described points pertain to the weaving method in which the reciprocatory shedding system is used, they are also applicable to a large extent even if the said shedding system is replaced by the existing rotary shedding systems. This is because the known rotary shedding methods have been primarily devised to handle yarns and not tape-like materials. Because the cross-sectional geometries of the yarns and tape-like materials are different, the existing rotary shedding methods are not suitable to handle tape-like warp and weft. To exemplify, a relevant shortcoming of the existing rotary shedding design is that the longitudinal open-end of the picking channel when combined with a rotary shedding system never faces in the direction of the fabric-fell. As a consequence, the pick cannot be laid directly and close to the fabric-fell and beating-up has to be necessarily carried out using either reciprocatory or rotary methods of beating-up with reed which will in turn cause severe lateral deformation and even damage to the flat tape-like weft as mentioned earlier. Also, these methods are limited in their constructional design and function and cannot be adopted to produce more than one fabric at a time even if they form multiple sequential sheds. The novelties of the present invention will become clear through the description and illustrations that follow.